Library Insert Alert

Dear all,

I fnd the backup job always alert the Library insert message after it had been ran on 2 or 3 Sundays. Sunday is the beginning of backup cycle. The BE will change the tapes when the new backup cycle begins. I check the media writable peroid is only 1 day. But if I restart the BE server, the job is working normally, no need to do anything. 

my BE is 2012 v14.0 Rev.1798 64bit, windows 2008 R2 Standard SP1. The tape library is IBM DS 3524.

Do you have the same problem, and how to slove it?

Thanks.

Jerry